We have drills where we step into a horse stance and block, strike, or block and strike simultaneously. Is this similar to what you are describing?Yes because there is more than one type of punch.
Straight punch and circular punch do not use the same power generation.
Circular punch and vertical backfist do not use the same power generation.
I also think Jab and Straight punch use different power generation as well.
So, some clarity here.
Kung Wang was speaking of horse stance and straight punch, but what came to my mind was the vertical back fist in Sei Ping. But now I'm focusing on the Straight Punch that Kung Fu wang is talking about it.
So, In Jow Ga we teach Jab + Step together. That's the technique most people have difficulty with. But a lot of the CMA strikes ue the step + punch at the same time even if it's not a jab.